The present invention provides a layered double hydroxide with improved conductivity, a layered double hydroxide and a composite material containing the layered double hydroxide. The layered double hydroxide is represented by the general formula: [Mg2+(1-y)M1α+y]1-x[Al3+(1-z)M2β+z]x(OH)2An−x/n.mH2O, wherein 0.1≤x≤0.4, 0≤y≤0.95, and 0≤z≤0.95, provided that both y and z are not 0 at the same time; α=1 or 2; β=2 or 3; An− is an n-valent anion, provided that n is an integer of 1 or greater; m≥0; M1α+ is a cation of at least one substituent element selected from monovalent elements, transition metal elements, and other elements with an ionic radius greater than that of Mg2+; and M2β+ is a cation of at least one element selected from divalent elements, transition metals, and other elements with an ionic radius greater than that of Al3+.